Answer is: a) in the presence of a base.
Phenolphthalein is colorless in acidic solutions and pink in basic solutions.
Acid-base indicators are usually weak acids or bases and they are chemical detectors for hydrogen or hydronium cations.
Example for acid-base indicator is phenolphthalein (molecular formula C₂₀H₁₄O₄).
When solution turns phenolphthalein pink, it means it is basic (pH>7).
The chemical formula for chlorophyll is C55H72O5N4<span>Mg. Only 1 of the 137 atoms comes from magnesium.
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Transferring or sharing electrons between atoms forms a covalent bond.<span> Covalent
bonding is when atoms share electrons. It is a chemical bond that involves the
sharing of electron pairs. These pairs are called bonding pairs. Examples of
compounds that has covalent bonds are CO2, organic compounds, lipids and
proteins.</span>
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